Wind-dispersed seeds common among maple trees were a key source of inspiration for the light-controlled robot. Photo: Jianfeng Yang / Tampere University

Science and technology

Researchers at Tampere University in Finland and the University of Pittsburgh in the USA have unveiled a groundbreaking tiny robot that mimics the graceful descent of falling maple seeds. This innovative device has the potential to revolutionize real-time environmental monitoring and sample delivery in hard-to-reach areas such as deserts, mountains, cliffs, and open seas.

At Tampere University, Professor Hao Zeng and Doctoral Researcher Jianfeng Yang, along with their Light Robots research group, have designed polymeric gliding structures inspired by nature.

Their collaboration with Professor M. Ravi Shankar from the University of Pittsburgh Swanson School of Engineering led to the development of a light-activated smart material that controls the gliding motion of an artificial maple seed.

In nature, maple seeds use their winged samaras to glide gently to the ground, aided by the wind. By replicating this natural design with advanced materials, the researchers have created an artificial maple seed that can be controlled using light. This artificial seed can adjust its glide path and dispersal trajectory, making it an ideal candidate for various applications in environmental monitoring.

The new technology surpasses natural seeds in adaptability. The researchers used azobenzene-based light-deformable liquid crystal elastomer, which enables reversible photochemical deformation, allowing for precise tuning of aerodynamic properties. This innovation means that the artificial seeds can achieve adjustable terminal velocities, rotation rates, and hovering positions, enhancing their wind-assisted long-distance travel through self-rotation.

In early 2023, Zeng and Yang released their first prototype, a dandelion seed-like mini robot, under the project Flying Aero-robots based on Light Responsive Materials Assembly (FAIRY). Funded by the Research Council of Finland, this project began in September 2021 and will continue until August 2026.

These light-controlled robots are designed to be released into the atmosphere, utilizing passive flight to disperse widely through interactions with surrounding airflows. Equipped with GPS and various sensors, they can provide real-time monitoring of local environmental indicators such as pH levels and heavy metal concentrations. This capability could be a game changer for fields like search-and-rescue, endangered species studies, and infrastructure monitoring.

"Nature offers ingenious templates for movement, feeding, and reproduction, often through simple yet highly functional mechanical designs," says Shankar. "With advances in photosensitive materials, we can now dictate mechanical behavior at nearly the molecular level. This opens up possibilities for creating micro-robots, drones, and probes that can access previously unreachable areas and relay critical information."

The research, detailed in the article "Photochemical Responsive Polymer Films Enable Tunable Gliding Flight" by Jianfeng Yang, M. Ravi Shankar, and Hao Zeng, was published in Nature Communications on June 1, 2024. This breakthrough underscores the potential of light-controlled mini robots to transform environmental monitoring and various other fields.